The present invention relates to stereo echo suppressing devices, echo suppressing devices, stereo echo suppressing methods, and non-transitory computer-readable recording medium storing stereo echo suppressing program. For example, the present invention can be applied to a stereo echo suppressing device used for a teleconferencing system and an audio conferencing system.
For example, in an amplifying call system such as the teleconferencing system and the audio conferencing system, sounds emitted from a loudspeaker (here, the “sound” includes acoustic, voice, and the like) input to a microphone as acoustic echo signals and return to a talker side. The acoustic echo signals seriously hinder telephone calls. Therefore, many studies and developments on acoustic echo suppressing methods have been performed.
One of techniques for suppressing acoustic echo signals includes a technique using an echo canceller. The echo canceller is a device for suppressing an acoustic echo signal by estimating echo path characteristics (spatial transfer characteristics) between a loudspeaker and a microphone with an adaptive filter; calculating an estimation echo signal by convolving a far-end output signal with the echo path characteristics estimated; and subtracting the estimation echo signal from an near-end input signal.
The echo canceller tends to be composed of a single loudspeaker. However, the teleconferencing system, the audio conferencing system, or the like each tends to be composed of two loudspeakers so as to output stereo signals. “ISCIE Journal ‘Systems, Control and Information’, vol. 46, No. 12, pp. 724-732 (2002), Stereophonic Acoustic Echo Cancellation: An Overview and Solutions, Shoji MAKINO, and Suehiro SHIMAUCHI” (Non-Patent Literature 1) proposes a stereo echo canceller that causes an echo canceller to be compatible with stereo output and suppresses acoustic echo signals in such case.